JP2003504264A - Master cylinder device - Google Patents

Abstract

(57) Abstract: A master cylinder device 10 for a vehicle hydraulic brake device is formed in the housing along an axis A with at least one filling chamber 18 and a first pressure chamber 22 therein. And a bore 16 defined therein. The filling piston 38 and the connected first pressure piston 40 discharge fluid from the filling chamber 18 to the suction side of the hydraulic pump 60, the discharge end of which pumps the pumped fluid to the first brake. Discharge into the circuit 64 and from the first pressure chamber 22 into the first brake circuit 64. The filling piston 38 and the first pressure piston 40 are movable with respect to each other by a limited distance s along the axis A in order to achieve the desired so-called "introduction operation". In addition, the filling piston 38 and the first pressure piston 40 are separated from each other by a spring force, the pistons 38 and 40 pushing the pistons apart from each other, pushing them apart from each other. After having moved one another only, the filling pistons 38 are spring-biased from one another in such a way that they are firmly connected to the first pressure piston 40.

Description

Detailed Description of the Invention

The invention relates to a master cylinder device for a hydraulic brake system of a vehicle according to the preamble of claim 1.

A master cylinder device of this kind is known from German Patent No. 196 20 228 A1. The master cylinder described therein is operable with an upstream brake booster, which is operable independently of the driver, so as to allow the braking device to be activated without the need for the driver's foot effort. To aim. Functions in which the individual wheels of the vehicle must be braked without the driver actuating the brake, for example functions such as traction control or vehicle power control, are realized only by such a method. A sufficiently large braking force
In order to make it available for such a function, German patent 196 20 228A.
The pressure boost of the master cylinder described in No. 1 can be switched. To prevent long pedal travels that occur at larger pressure boost positions due to the small hydraulically effective area, hydraulic pumps provide brake fluid from the fill chamber first. Pump into a first brake circuit associated with a pressure chamber. This master cylinder device according to German Patent No. 196 20 228 A1 is neither intended nor intended for use without upstream brake boosters.

An object of the present invention is a master cylinder device of simple structure for a hydraulic brake system of a vehicle, which can be operated without an upstream brake booster and has the performance of a conventional brake booster / master cylinder device. Providing a master cylinder device which functions in a corresponding manner.

The above-mentioned object is, in a master cylinder device of the type described at the outset, that the filling piston and the first pressure piston are movable relative to each other to a limited extent along their common main axis, the filling piston and the first pressure piston The pistons are spring biased with respect to each other in such a way that they are pushed away from each other and the filling piston and the first pressure piston are oriented towards each other by the above-mentioned degree against the spring force pushing them apart from each other. It is realized according to the present invention by firmly connecting to each other after being moved.

The effect obtained by this is that at first, only the filling piston is displaced with respect to the first pressure piston and discharges fluid from the filling chamber to the hydraulic pump, which then In order to supply the above-mentioned fluid to the first brake circuit and thus increase the pressure therein according to the amount of fluid discharged from the filling chamber into the first brake circuit, the operating force in the first stage of the braking action is increased. Is small.
This means that in the first stage of braking, the actuating force introduced by the driver is increased to a relatively large extent, so that with a sufficiently sized braking device to operate effectively. It means giving the driver the feeling of. The above-mentioned performance of the master cylinder device according to the invention corresponds to that of a conventional (vacuum) brake booster master cylinder, which in this device was made of a repulsive elastic material arranged between the brake booster and the master cylinder. The so-called recoil disc cooperates with the so-called sensing disc to ensure that the introduced actuating force is increased to a much greater extent at the beginning of actuation than in the later stages of braking.

Relative movement between the fill piston and the pressure piston occurs because the fluid is simply drained from the fill chamber. That is, the fill chamber remains unpressurized, while in the first pressure chamber connected to the first brake circuit in a fluid transfer manner, the fill piston moves to expel the fill chamber. The fluid pumped by the hydraulic pump into the first brake circuit causes an increase in pressure in the first brake circuit. Therefore,
The first pressure piston remains stationary with respect to the filling piston during the first stage of operation, and as the pressure in the first brake circuit rises, the first pressure piston operates towards the filling piston. Moves in the opposite direction. While the above relative movement takes place, the limited distance approaches zero and in time the first pressure piston firmly connects to the filling piston. This causes the two pistons to behave like a single piston when further displaced in the actuation direction. From the time point above, the pressure in the first pressure chamber reacts to the filling piston via the first pressure piston,
Then, it is transmitted to the driver. A higher actuation force from the driver is required for the brake pressure to increase further. The driver must react the pressure in the first pressure chamber to displace the first pressure piston. However, at the same time, when the first pressure piston and the filling piston connected to the first pressure piston are further displaced in the operating direction, further fluid is discharged from the filling chamber to the hydraulic pump, The pump supplies the above fluid under elevated pressure to the first brake circuit. Therefore, this actuation force introduced by the driver is still enhanced, but is no longer enhanced by as much a factor as at the beginning of actuation.

In one preferred embodiment of the master cylinder device according to the invention, the stop defines an inactive position of the first pressure piston, from which the piston moves in the operating direction and the operating direction. It can be displaced in both opposite directions. A spring acting in the actuating direction pushes the first pressure piston towards said stop as soon as the first pressure piston is displaced from its inoperative position opposite the actuating direction. The stopper retains the force of the spring when the first pressure piston is in the inoperative position, whereby the first pressure piston is in its inoperative position or in a position displaced in the operating direction. It is preferably designed so that the force of the spring does not act on the first pressure piston. Setting the magnitude of the spring force makes it possible to define the pressure level above which the first pressure piston will connect with the filling piston. According to one embodiment, the stopper and the spring are arranged in the first pressure chamber. Alternatively, the spring may be arranged between the filling piston and the first pressure piston and thus act simultaneously as a filling piston and as a return spring for the first pressure piston.

If the above-mentioned spring is not arranged between the filling piston and the first pressure chamber, it is preferable to provide a further spring which biases the filling piston in the direction opposite to the operating direction. At the end of operation, the spring pushes the filling piston back into its original position.

The first pressure piston and the filling piston may have equal hydraulic effective areas. However, preferably, the hydraulic effective area of the first pressure piston is smaller than the hydraulic effective area of the filling piston, and the boost factor is excessively reduced during the connection between the filling piston and the first pressure piston. And when the hydraulic pump fails, it is still possible to build up pressure to meet certain minimum requirements.

The standard modern vehicle braking system has at least two braking circuits, not just one, so that in the preferred embodiment of the master cylinder system according to the invention, the bore of the master cylinder is provided. A second pressure chamber is defined in the second pressure chamber, and a second pressure piston is disposed in the second pressure chamber, and the second pressure piston is a fluid when the second pressure piston is displaced in a pressure accumulation direction. From the second pressure chamber into the second brake circuit.

Used in the master cylinder device according to the invention, only the fluid supplied to and discharged from the filling chamber is pumped into the first brake circuit, so that it is not necessary to self-prime. The hydraulic pump can be a separate pump, but is preferably a wheel slip control pump, which is a standard device in more and more vehicles today.

The accompanying drawings show a master cylinder device 10 comprising a master cylinder 12, in a housing 14 of which a bore 16 is formed along an axis A. Within the bore 16 there is defined a fill chamber 18 having an outlet 20, a first pressure chamber 22 separate from the fill chamber 18 and having an outlet 24, and a second pressure chamber 26 having an outlet 28. Has been done. In the operative state of the master cylinder 12, the filling chamber 18, the first pressure chamber 22 and the second pressure chamber 26 are completely filled with hydraulic fluid, which hydraulic fluid from a storage container not shown. Through the connection openings 30, 32 and the master cylinder housing 14
Flow through the tubes 34, 36 formed in the chamber into the chambers 18, 22, 26.

The fill piston 38 associated with the fill chamber 18 is further guided within the bore 16 in a sealed and displaceable manner. A first pressure piston 40 associated with the first pressure chamber 22 is connected to the fill piston 38, which is in a sealed and displaceable manner within the small diameter portion 42 of the bore 16. Be guided. In practice, the small diameter section 42 described above may also be in the form of a guide ring that is inserted into and seals against the bore 16.

The position of the first pressure piston 40 shown in the drawing is its inoperative position defined by the stopper 44 within the first pressure chamber 22, ie its initial position.
A compression spring 46, supported by its end against the small diameter portion 42, presses against the stopper 44 a ring 48 through which the first pressure piston 40 extends. This first pressure piston 40 has at its free end an annular collar 50 with an outer diameter larger than the diameter of the opening provided in the ring 48.

At the other end facing the filling piston 38, the first pressure piston 40 is provided with a further annular ring, in the present case, carried by a plurality of arms 54 integrally formed with the filling piston 38. A collar 52 is provided. As is apparent from the drawings, the arm 54 forms a guide and a stop for the annular collar 52, so that the first pressure piston 40 is provided with a filling piston 38 along the axis A a distance s.
Is displaceable with respect to.

Finally, in the present embodiment, the second pressure piston 56, which in the form of a floating piston and is associated with the second pressure chamber 26, includes a bore 16 of the master cylinder 12.
Further guided in a sealed and displaceable manner within.

The outlet 20 of the filling chamber 18 is connected by a tube 58 to the suction side of a hydraulic pump 60 so that it can carry a fluid. Located within the tube 58 is a valve 62, the purpose of which will be described in more detail below.

The outlet 24 of the first pressure chamber 22 is connected in a fluid-carrying manner with a first brake circuit 64 to which two wheel brakes 66, 68 are associated. Similarly,
The discharge end of the hydraulic pump 60 described above is connected to the first brake circuit 6 so as to carry the fluid.
4 is connected.

The outlet 28 of the second pressure chamber 26 is connected in fluid communication with a second brake circuit 70, which in the present case comprises two further brake circuits. Wheel brakes 72, 74 are involved and a further hydraulic pump 60 'is arranged in the second brake circuit. As is common to wheel slip controlled vehicle braking systems and as such is known to those skilled in the art, a solenoid valve, shown in the drawings but not described in detail, is a wheel brake 66.
, 68, 72, 74.

The illustrated master cylinder device 10 operates as follows. When an actuating force F is introduced into the filling piston 38 via a brake pedal (not shown), the filling piston is displaced to the left and brings fluid from the filling chamber 18 through the outlet 20 into the pipe 58 which reaches the hydraulic pump 60. Discharge. In the above case, the valve 62 is located in its normal, pierced position. Substantially at the same time that the master cylinder 12 begins to operate, for example through the introduction of an actuation force F that can be detected by the displacement of the filling piston 38, the hydraulic pump 60 starts and all fluid discharged from the filling chamber 38 The quantity is discharged into the first brake circuit 64, after which a corresponding increase in pressure occurs in the first brake circuit. The pressure is transmitted into the first pressure chamber 22, which acts on the first pressure piston 40. Since the ring 48 is biased towards the stopper 44 and against which the first pressure piston 40 is supported by its annular collar 50, the first pressure piston 40 does not initially change its position. . Thus, at the start of braking, the filling piston 38 is displaced with respect to the first pressure piston 40 and at the same time reduces the distance s.

During the course of braking, the pressure in the first pressure chamber 22 rises, and at some point exceeds the force of the spring 46, which is then compressed and thus the first Pressure piston 40 moves in a direction opposite to the direction of operation toward filling piston 38,
Therefore, the distance s is further shortened.

If the pressure in the first pressure chamber 40 still rises further, the first pressure piston 40 abuts the filling piston 38 after surpassing the play s and is effective during the further operating process. It is pressed against the filling piston 38 by force. Therefore,
After exceeding the distance s, the filling piston 38 is connected to a first pressure piston 40 and both pistons 38, 40 act as if they were a single piston during the further course of the braking operation. .

The pressure present in the first pressure chamber 40 and the first brake circuit 64 immediately leads to the second pressure chamber 26 and a second pressure chamber connected to the second pressure chamber 26 via a second pressure piston. It is transmitted to the second brake circuit 70. Before connecting the filling piston 38 to the first pressure piston 40, the pressure in the brake circuit 64, 70 is determined only by the pump 60, while in the brake circuit 64, 70 after connecting the two pistons 38, 40. The pressure present at consists of the pressure portion supplied by the hydraulic pump 60 and the pressure portion due to the actuation force F introduced via the pistons 38, 40. This means that the boost factor of the master cylinder device 10 is greater at the beginning of the braking operation than after the two pistons 38, 40 are connected. At the time of connection, since the pump 60 can already operate in the brake-enhanced state, the driver assumes that the reaction force acting on the filling piston 38 and the brake pedal (not shown) after the connection is reduced. Only recognizable.

During the return movement (return stroke) of the two pistons, the annular collar 50 abuts the ring 48, so that the filling piston 38 is acted upon when the spring 46 can act on the first pressure piston 40. Separate from the first pressure piston 40. A return spring, not shown in the drawing, then pushes the filling piston 38 back into its original position, resetting the distance s between the filling piston 38 and the annular collar 52 of the first pressure piston 40.

A second hydraulic pump 60 ′ shown in the drawing is used in a conventional manner so as to generate a pressure in the second brake circuit 70 during wheel slip control activation. However, if desired, the hydraulic circuit may alternatively include a second hydraulic pump 60.
It may be designed so as to be distributable by ‘. The hydraulic pump 60 then also produces pressure in both brake circuits 64, 70.

In the illustrated and described master cylinder apparatus 10, the hydraulic pump 60 provides pressure augmentation so that the use of conventional brake boost is not required. However, if the master cylinder device 10 is operated by a brake booster not shown in the drawings, or if the pump 60 is defective, the valve 62
Is controlled to its closed position, so that brake pressure can also build up in the filling chamber 38. The check valve 76 in the above embodiment allows fluid to overflow from the fill chamber 38 into the first pressure chamber 22. As a result, the brake pressure builds up in all chambers 18, 22, and 26 at the same time,
There is no longer any relative displacement between the pistons 38, 40.

[Brief description of drawings]

FIG. 1 is a longitudinal cross-sectional view of one embodiment of a master cylinder device according to the present invention.

[Procedure for Amendment] Submission for translation of Article 34 Amendment of Patent Cooperation Treaty

[Submission date] June 18, 2001 (2001.6.18)

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Claims

[Correction method] Change

[Contents of correction]

[Claims]

Claims (7)

[Claims] 1. A housing (14) and at least one filling chamber (18) and a first pressure chamber (2) formed in the housing along an axis (A).
A bore (16) defined by 2), a hydraulic pump (60) which discharges the fluid pumped from the discharge end into the first brake circuit (64), A filling piston (38) and a first pressure piston (
40), the filling pistons (38) expel fluid from the filling chamber (18) to the suction side of the hydraulic pump (60) when displaced in respective pressure increasing directions, A first pressure piston (40) is adapted to discharge fluid from a first pressure chamber (22) into a first brake circuit (64), a master cylinder arrangement for a vehicle hydraulic brake arrangement. At (10), the filling piston (38) and the first pressure piston (40) are movable relative to each other for a limited distance (s) along the axis (A), the filling piston (38) and the first pressure piston (40) The pressure pistons (40) are spring biased relative to each other in such a way that they are pushed apart from each other, and the filling piston (38) and the first pressure piston (40) push these pistons apart from each other. When it moved toward each other by a distance (s) against the spring force to the master cylinder device, characterized in that is adapted to rigidly connect to each other. 2. A master cylinder arrangement according to claim 1, further comprising a stopper (44) defining an inactive position of the first pressure piston (40), the first pressure piston (40) being in the operating direction. As soon as it is displaced out of its inoperative position, the spring (46) acting in the actuating direction pushes the first pressure piston (40) towards said stopper (44). The master cylinder device is characterized by 3. The master cylinder device according to claim 2, wherein the stopper (4
4) A master cylinder device, characterized in that the spring (46) and the spring (46) are arranged in the first pressure chamber (22). 4. A master cylinder arrangement according to any one of claims 1 to 3, characterized in that a spring biases the filling piston (38) in the direction opposite to the actuating direction. 5. A master cylinder arrangement according to any one of claims 1 to 4, characterized in that the first pressure piston (40) has a smaller hydraulic effective area than the filling piston (38). And master cylinder device. 6. A master cylinder arrangement according to claim 1, wherein a second pressure chamber (26) is defined in the bore (16) and a second pressure piston (56) is provided. A master cylinder device, characterized in that when displaced in a direction of increasing pressure, fluid is discharged from the second pressure chamber (26) into the second brake circuit (70). 7. A master cylinder device according to any one of claims 1 to 6, characterized in that the hydraulic pump (60) is a pump of a wheel slip control device.